I call JavaScript the language of the Web. It's what I've used, and am using, to develop all my Browser-based Games.
I use Javascript as my client-side (in your browser) scripting, and PHP as my server-side (on my server) scripting. You can read more about this on my Code page.
You can find a good general introduction to Javascript at JavaScript.info.
W3 Schools provides another introduction, but also includes more detailed information about JavaScript as well.
And, you can also look at how I've used JavaScript in my games by simply right-clicking on the game's page and then clicking on "View Page Source" (in Firefox - other browsers are similar).
M.D.J. 2021/07/20